Oil mist separator

ABSTRACT

An oil mist separator that is provided at a portion further up than a cylinder head in an internal combustion engine body, includes: an oil mist separating unit that separates oil mist contained in a blow-by gas that is generated from the internal combustion engine body, wherein the oil mist separating unit includes a first member that is arranged in a lower portion and has a partitioning wall shape, and a second member that is arranged above the first member, and includes a first blow-by gas inlet port which is provided at a position further up than the first member and through which the blow-by gas flows into the oil mist separating unit.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 U.S.C. §119 to Japanese Patent Application 2014-254761, filed on Dec. 17, 2014, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

This disclosure relates to an oil mist separator.

BACKGROUND DISCUSSION

In the related art, an oil mist separator that separates oil mist included in a blow-by gas has been known (for example, refer to Japanese Patent No. 4510108 (Reference 1)).

Reference 1 discloses the oil mist separator configured to include a lower case having a single gas inlet port, a cyclone unit in which a cyclone is formed, a gas discharge unit, and an upper case. The oil mist separator is arranged in a head cover of an automotive engine. The lower case functions as a partitioning member that separates a region (a cam chamber), in which a camshaft or the like is arranged, from a region in which the oil mist separator is arranged, in the head cover. The gas inlet port of the lower case is arranged at a position that protrudes downward in the lower case, and the gas inlet port is provided at a position on a side lower than a bottom surface of the lower case.

However, in the oil mist separator disclosed in Reference 1, since the gas inlet port is arranged at a position that protrudes downward in the lower case, oil scattered from the camshaft or the like may directly enter the gas inlet port, or the gas inlet port may be covered by oil in a case where the oil mist separator is relatively inclined with respect to the oil level of oil when an automobile travels uphill or downhill or turns. Therefore, there is a problem in that oil may be easily sucked into the oil mist separator. Suction of oil becomes a hindrance to the improvement of separation properties of the oil mist separator.

SUMMARY

Thus, a need exists for an oil mist separator which is not susceptible to the drawback mentioned above.

An oil mist separator according to an aspect of this disclosure is provided at a portion further up than a cylinder head in an internal combustion engine body, and includes an oil mist separating unit that separates oil mist contained in a blow-by gas that is generated from the internal combustion engine body. The oil mist separating unit includes a first member that is arranged in a lower portion and has a partitioning wall shape, and a second member that is arranged above the first member, and includes a first blow-by gas inlet port which is provided at a position further up than the first member and through which the blow-by gas flows into the oil mist separating unit.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and additional features and characteristics of this disclosure will become more apparent from the following detailed description considered with the reference to the accompanying drawings, wherein:

FIG. 1 is a schematic view schematically illustrating an entire configuration of an oil mist separator according to an embodiment disclosed here;

FIG. 2 is an exploded perspective view illustrating the entire configuration of the oil mist separator according to the embodiment disclosed here;

FIG. 3 is a sectional view taken along line III-III of FIG. 6;

FIG. 4 is a sectional view taken along line IV-IV of FIG. 6;

FIG. 5 is a bottom view of the oil mist separator according to the embodiment disclosed here;

FIG. 6 is a cross-sectional view taken along line VI-VI of FIG. 3;

FIG. 7 is a schematic sectional view illustrating an oil mist separator according to a first modification example of the embodiment disclosed here;

FIG. 8 is a schematic sectional view illustrating an oil mist separator according to a second modification example of the embodiment disclosed here; and

FIG. 9 is a bottom view illustrating a first blow-by gas inlet port according to a third modification example of the embodiment disclosed here.

DETAILED DESCRIPTION

Hereinafter, an embodiment disclosed here will be described with reference to the drawings.

First, the configuration of an oil mist separator 100 according to the embodiment disclosed here will be described with reference to FIGS. 1 to 6.

As illustrated in FIG. 1, the oil mist separator 100 is provided in an internal combustion engine (engine) body 90, and is a device that separates oil mist from a blow-by gas leaking from a space between a piston and a cylinder of the internal combustion engine body 90. The oil mist indicates atomized lubricating oil in the internal combustion engine body 90 such as engine oil.

The internal combustion engine body 90 is, for example, an automobile engine, and includes a cylinder head 91, and a cylinder head cover 92 (hereinafter, referred to as a head cover 92). Although not illustrated, the internal combustion engine body 90 includes a cylinder block, a crankcase, a cylinder, a piston, a connecting rod, a crankshaft, and the like. In addition, an intake manifold 95 that introduces intake air to the internal combustion engine body 90 is connected to the internal combustion engine body 90. A positive crankcase ventilation (PCV) system, which returns a blow-by gas BG to the intake air side (the intake manifold 95) to cause the blow-by gas to be re-combusted, is provided to the internal combustion engine body 90.

Specifically, in the internal combustion engine body 90, the cylinder head 91 and the intake manifold 95 communicate with each other through the oil mist separator 100. The blow-by gas BG is forcibly introduced, due to the intake negative pressure on the intake manifold 95 side, to the intake manifold 95 from the crankcase through the cylinder block, the cylinder head 91, and the oil mist separator 100. The blow-by gas BG is mixed with the intake air in the intake manifold 95 and is restored to a combustion chamber of the internal combustion engine body 90. The oil mist separator 100 separates (gas-liquid separation) oil from the blow-by gas BG containing oil mist while blow-by gas BG passes through the crankcase and the cylinder head 91.

The oil mist separator 100 is provided at a portion (Z1 direction) further up than the cylinder head 91 in the internal combustion engine body 90, and includes an oil mist separating unit 1 that separates oil mist contained in the blow-by gas BG that is generated from the internal combustion engine body 90. In the embodiment, the oil mist separating unit 1 is arranged at the portion further up than the cylinder head 91 and is in the head cover 92.

The oil mist separating unit 1 includes a first member 2 and a second member 3. The first member 2 is a member having a partitioning wall shape that is arranged in a lower portion (Z2 direction) in the oil mist separating unit 1. The second member 3 is arranged above the first member 2. In the embodiment, the second member 3 includes a first blow-by gas inlet port 31 which is provided at a position further up than the first member 2 and through which the blow-by gas BG flows into the oil mist separating unit 1. Further, all of the first member 2 and the second member 3 may be configured by a single member or may be configured by a combination of plural members.

The first member 2 includes a baffle plate 21 that is arranged to separate the head cover 92 from the cylinder head 91. The baffle plate 21 is a partitioning plate that separates a cam chamber 94 on a lower side in which a camshaft 93 is arranged, from a region (PCV chamber) on an upper side in which the oil mist separating unit 1 is arranged, in the head cover 92.

The second member 3 includes the head cover 92 as a cover member 32, and a separation structure 33. That is, in the embodiment, the oil mist separating unit 1 includes a part of the cylinder head cover 92 as the cover member 32 that covers the separation structure 33. In other words, the oil mist separating unit 1 is integrally formed with the head cover 92 in the head cover 92.

The separation structure 33 is provided with a separator 33 a that collects oil mist contained in the blow-by gas BG. The separator 33 a can adopt various systems such as a cyclone system which generates a swirl flow so as to separate the oil mist by centrifugal force, a filter system which causes the blow-by gas to pass through a filter member so as to collect oil mist, and an inertial impaction system which causes oil mist contained in the blow-by gas to collide with an impact plate (or a wall) so as to collect the oil mist. In the embodiment, as the separator 33 a, a cyclone unit 34, which will be described later, is provided.

Hereinafter, the configuration of the oil mist separating unit 1 of the embodiment will be described in detail with reference to FIGS. 2 to 6. FIGS. 2 to 6 illustrate a structure in which a part of the head cover 92 which configures the oil mist separating unit 1 (a part functioning as the cover member) is cut out. Hereinafter, a longer side direction of the oil mist separating unit 1 is referred to as an X direction, and a shorter side direction of the oil mist separating unit 1 is referred to as a Y direction.

As illustrated in FIG. 2, the first member 2 of the oil mist separating unit 1 includes the baffle plate 21 described above, and oil discharge pipes 22. The baffle plate 21 configures a lower surface portion (bottom surface portion) of the oil mist separating unit 1. A pair of oil discharge pipes 22 is provided on a lower surface side of the baffle plate 21 so as to protrude downward (Z2 direction). The oil discharge pipe 22 returns oil-liquid droplets after the separation, which are dropped onto an upper surface of the baffle plate 21, to the cam chamber 94 on the lower side (refer to FIG. 1).

In terms of a structure, the second member 3 includes the cover member 32 (the head cover 92), and a main body 40 and an inner cover unit 50 which configure the separation structure 33. In addition, the second member 3 includes a plurality of (four) cyclone units 34, and second blow-by gas inlet ports 35 through which the blow-by gas BG, which has flowed through the first blow-by gas inlet port 31 (refer to FIG. 3), flows into the plurality of cyclone units 34. These cyclone units 34, the first blow-by gas inlet port 31, and the second blow-by gas inlet port 35 are formed in the separation structure 33.

The cover member 32 has a box shape (rectangular parallelepiped shape) of which the lower surface side is open, and covers the separation structure 33 so as to accommodate the separation structure 33 therein. Since the cover member 32 is configured by the head cover 92 (refer to FIG. 1), the blow-by gas BG can be prevented from leaking to the outside. The cover member 32 includes a gas discharge port 32 a formed of a circular hole on the upper surface. The gas discharge port 32 a is connected to the intake manifold 95 side (refer to FIG. 1), and the blow-by gas BG after the separation of the oil mist is derived through the gas discharge port 32 a.

The main body 40 of the separation structure 33 has a box shape (rectangular parallelepiped shape), and the lower surface side thereof is bonded to the baffle plate 21. A pair of peripheral wall portions 41 configuring the cyclone units 34 is formed on the upper surface of the main body 40 so as to protrude upward (Z1 direction).

The inner cover unit 50 of the separation structure 33 has a size smaller than that of the cover member 32, and has a box shape (rectangular parallelepiped shape) of which the lower surface side is open. The inner cover unit 50 is provided to cover the main body 40 from the upper portion. Four opening portions 51, which act as discharge ports of the blow-by gas BG in the four cyclone units 34, are provided on the upper surface of the inner cover unit 50. As illustrated in FIGS. 3 and 4, the inner cover unit 50 and the main body 40 are configured as the separation structure 33 by being bonded to each other through a contact surface between an upper surface portion 52 of the inner cover unit 50 and an upper end of the peripheral wall portion 41. In this manner, a gap as a passage of the blow-by gas BG is formed between the inner cover unit 50 and the main body 40.

The first blow-by gas inlet port 31 is provided in a lower portion of a side portion 3 a of the second member 3. Specifically, the first blow-by gas inlet port 31 is formed by a gap between a lower end portion of a side surface portion 42 of the main body 40 and a lower end portion of a side surface portion 53 of the inner cover unit 50. That is, in the embodiment, the first blow-by gas inlet port 31 is arranged in a lower end portion of the side portion 3 a of the second member 3.

In the embodiment, the first blow-by gas inlet ports 31 are provided at multiple locations. Specifically, as illustrated in FIG. 5, the first blow-by gas inlet ports 31 (hatched portion) are provided at the locations on the X1 side, the X2 side, the Y1 side, and the Y2 side of the main body 40. Here, in the embodiment, the first blow-by gas inlet ports 31 are provided over the whole circumference of the side portion 3 a of the second member 3. That is, the entirety of the first blow-by gas inlet ports 31 is a single inlet port formed in a peripheral shape along the side portion 3 a. In this manner, the first blow-by gas inlet ports 31 are provided on each side surface of the four locations of the main body 40. The first blow-by gas inlet port 31 is configured to cause the blow-by gas BG to flow from the multiple locations (all horizontal directions including the X1 side, the X2 side, the Y1 side, and the Y2 side) of the main body 40.

As illustrated in FIG. 6, a pair of second blow-by gas inlet ports 35 is provided on an upper surface portion 43 (refer to FIG. 3) of the main body 40 in the vicinity of the four cyclone units 34. The pair of second blow-by gas inlet ports 35 is arranged at positions between the two pairs (four in total) of cyclone units 34. The second blow-by gas inlet ports 35 are formed by gaps between the central end portions of the pair of peripheral wall portions 41 of the main body 40. That is, the second blow-by gas inlet port 35 that is opened to the Y1 side is formed by a gap between end portions 41 a on the Y1 side of the pair of peripheral wall portions 41, and the second blow-by gas inlet port 35 that is opened to the Y2 side is formed by a gap between end portions 41 b on the Y2 side of the pair of peripheral wall portions 41.

In this manner, the second member 3 includes the second blow-by gas inlet ports 35, the number (two on the Y1 side and the Y2 side) of which is smaller than the number of the multiple locations (multiple locations including four locations on the X1 side, the X2 side, the Y1 side, and the Y2 side) where the first blow-by gas inlet ports 31 are provided.

As illustrated in FIGS. 3 and 4, the second blow-by gas inlet port 35 is arranged at a portion (Z1 direction) further up than the first blow-by gas inlet port 31. Further, the second member 3 includes a gas passage 36 that extends upward from the first blow-by gas inlet port 31 to be connected to the second blow-by gas inlet port 35. That is, a first passage portion 36 a that extends upward from the first blow-by gas inlet port 31 is configured by a gap between the side surface portion 42 of the main body 40 and the side surface portion 53 of the inner cover unit 50. In addition, a second passage portion 36 b that extends from an upper end of the first passage portion 36 a along the upper surface portion 43 of the main body 40 is configured by a gap between the upper surface portion 43 of the main body 40 and the upper surface portion 52 of the inner cover unit 50.

As illustrated in FIG. 6, the first passage portion 36 a is a peripheral shaped passage portion that communicates with the peripheral shaped first blow-by gas inlet port 31. In addition, the second passage portion 36 b is a flat passage portion that connects the upper end portion of the first passage portion 36 a on the outer peripheral side to the second blow-by gas inlet port 35 on the center.

Each of the four cyclone units 34 is a cylindrical space surrounded by the peripheral wall portion 41 on the upper surface of the main body 40. The two cyclone units 34 are provided to each of the pair of the peripheral wall portions 41, and two pairs (four in total) of cyclone units 34 are configured. Each of the four cyclone units 34 includes a connection passage 34 a formed of a gap of the peripheral wall portion 41. Each connection passage 34 a communicates with a central region 44 between the pair of second blow-by gas inlet ports 35. The blow-by gas BG introduced from the pair of second blow-by gas inlet ports 35 to the central region 44 is introduced to each cyclone unit 34 through the connection passage 34 a. The pair of second blow-by gas inlet ports 35 functions as a common inlet port for the four cyclone units 34. An opening width W1 of the second blow-by gas inlet port 35 is greater than an opening width (passage width) W2 of the connection passage 34 a.

The two pairs of (four) cyclone units 34, the connection passages 34 a, and the peripheral wall portions 41 are formed to be symmetric with respect to the central region 44 in which the second blow-by gas inlet port 35 is arranged. The respective connection passages 34 a are opened to the central region 44 so as to face each other. Accordingly, paths for introducing the blow-by gas BG from the central region 44 to each of the four cyclone units 34 have approximately the same introduction length and resistance in the flow path. As a result, it is possible to uniformly distribute the blow-by gas BG from the second blow-by gas inlet port 35 to the four cyclone units 34.

As illustrated in FIG. 4, upper and lower end portions of the cyclone unit 34 are opened. A lower opening portion 34 b communicates with an internal space surrounded by the main body 40 and the baffle plate 21. The upper end of the cyclone unit 34 uses the inner cover unit 50 as a cover, and communicates with the upper surface side of the inner cover unit 50 through the opening portion 51 of the inner cover unit 50. The blow-by gas BG forms a flow of swirling along the wall surface (inner peripheral surface of the peripheral wall portion 41) in the cyclone unit 34, and is separated from the oil mist by causing the oil mist to adhere to the wall surface by the centrifugal force of the swirl flow. The blow-by gas BG after the separation is discharged, by the intake negative pressure, to the upper surface side of the inner cover unit 50 through the opening portion 51. The oil-liquid droplets separated in the cyclone unit 34 are discharged to the upper surface side of the baffle plate 21 through the lower opening portion 34 b of the cyclone unit 34.

In the upper surface side of the inner cover unit 50, the cover member 32 (the head cover 92) includes a discharge passage 32 b for the blow-by gas BG. Specifically, the discharge passage 32 b is configured by a gap between the upper surface portion 52 of the inner cover unit 50 and an upper surface portion 32 c of the cover member 32. As illustrated in FIG. 3, the discharge passage 32 b communicates with the gas discharge port 32 a of the upper surface portion 32 c of the cover member 32. The blow-by gas BG that has entered the discharge passage 32 b from the four cyclone units 34 through the respective opening portions 51 (refer to FIG. 4), is merged in the discharge passage 32 b, and is restored from the gas discharge port 32 a to the intake manifold 95 side.

In addition, a space portion 37 that is different from the discharge passage 32 b is provided between the side surface of the separation structure 33 (the inner cover unit 50) and the cover member 32. That is, the peripheral shaped space portion 37 (refer to FIG. 6) is formed between the outer side surface (the side surface portion 53) of the inner cover unit 50 and the inner side surface of the cover member 32. The space portion 37 is a closed space that is separated from the discharge passage 32 b on the upper surface side. The space portion 37 functions as a thermal insulation space of the oil mist separating unit 1. That is, since the separation and collection properties of the oil mist are degraded due to freezing under a cold environment in which the oil mist separating unit 1 is frozen, it is preferable to warm the oil mist separating unit 1 using the warm-up so as to quickly thaw the oil mist separating unit 1. The space portion 37 can prevent the heat inside the oil mist separating unit 1 during the warm-up from being lost by the outside air, and thus rapid warm-up (thawing out) can be possible.

Next, the flow of the blow-by gas in the oil mist separator 100 according to the embodiment will be described.

First, as illustrated in FIG. 1, the blow-by gas BG that has flowed up to the head cover 92 is sucked into the first blow-by gas inlet port 31 that is arranged at a position further up than the first member 2 (the baffle plate 21). At this time, as illustrated in FIG. 3, the oil-liquid droplets that have flown up by the camshaft 93 (refer to FIG. 1) are blocked by the baffle plate 21. As a result, entering of the oil-liquid droplets into the first blow-by gas inlet port 31 is suppressed.

As illustrated in FIG. 5, the blow-by gas BG flows into the oil mist separating unit 1 through the first blow-by gas inlet port 31 from a plurality of locations such as the X1 direction side, the X2 direction side, the Y1 direction side, and the Y2 direction side. Here, in a case where the oil mist separator 100 is inclined when an automobile travels uphill or downhill, or in a case where centrifugal force acts when an automobile turns, the oil-liquid droplets adhering to the inner side of the head cover 92 or the lower surface of the baffle plate 21 may cover a part of the first blow-by gas inlet port 31. In a case where some locations of the first blow-by gas inlet port 31 are covered by oil, the blow-by gas BG flows through other locations which are not covered by the oil.

As illustrated in FIG. 4, the blow-by gas BG having flowed through the first blow-by gas inlet port 31 rises through the first passage portion 36 a and then flows into the second passage portion 36 b. In the second passage portion 36 b, as illustrated in FIG. 6, the blow-by gas BG flows into the pair of second blow-by gas inlet ports 35 at the center from the Y1 direction side or the Y2 direction side. The blow-by gas BG that has flowed from the first blow-by gas inlet port 31 in the X1 side and the X2 side, makes a detour of the peripheral wall portion 41 and then flows into the second blow-by gas inlet port 35. In this manner, the flowing paths of the blow-by gas BG from the first blow-by gas inlet port 31 to the second blow-by gas inlet port 35 are different depending on the flowing position, but finally reach the second blow-by gas inlet port 35 at the center.

The blow-by gas BG that has flowed from the second blow-by gas inlet port 35 to the central region 44, flows through the connection passage 34 a into each of the four cyclone units 34. In the embodiment, since the cyclone units 34 are symmetric with respect to the central region 44, the deviation of the flowing amount is suppressed, and the blow-by gas BG is uniformly distributed to the four cyclone units 34. As a result, even in a case where the flowing paths of the blow-by gas BG from the first blow-by gas inlet port 31 to the second blow-by gas inlet port 35 are not fixed as in the embodiment, the variation in velocity of the swirl flow of the cyclone unit 34 is suppressed, and the oil mist is efficiently collected in each cyclone unit 34.

As illustrated in FIGS. 3 and 4, the blow-by gas BG from which the oil mist is separated in each cyclone unit 34 is discharged through the opening portion 51 of the inner cover unit 50 (refer to FIG. 4), the discharge passage 32 b, and the gas discharge port 32 a (refer to FIG. 3).

In the embodiment, the following effects can be obtained.

That is, in the embodiment, as described above, the oil mist separating unit 1 is provided which includes the first member 2 that is arranged in a lower portion and has a partitioning wall shape, and the second member 3 that is arranged above the first member 2, and includes the first blow-by gas inlet port 31 which is provided at a position further up than the first member 2 and through which the blow-by gas BG flows into the oil mist separating unit 1. In this manner, while the first member 2 separates the cam chamber 94 from the oil mist separating unit 1, the blow-by gas BG can flow through the first blow-by gas inlet port 31 that is provided at a position further up than the first member 2. As a result, it is possible to suppress entering of the oil, which is scattered from the camshaft 93 or the like, into the first blow-by gas inlet port 31. In addition, even in a case where the oil level of oil is relatively inclined at the time of an uphill climb, it is possible to suppress the covering of the first blow-by gas inlet port 31 by the oil. As a result, suction of the oil into the oil mist separator 100 can be suppressed.

In the embodiment, as described above, the first blow-by gas inlet ports 31 are provided at multiple locations. In this manner, even in a case where any one of the first blow-by gas inlet ports 31 that are provided at multiple locations is covered by the oil, it is possible for the blow-by gas BG to flow through the first blow-by gas inlet ports 31 that are provided at other locations. As a result, it is possible to further suppress suction of the oil. In addition, it is possible to easily increase the total opening area of the first blow-by gas inlet ports 31. As a result, since the flow rate of the blow-by gas BG in the first blow-by gas inlet port 31 can be reduced, it is possible to suppress the suction of the oil.

In the embodiment, as described above, the first blow-by gas inlet port 31 is provided at a lower portion of the side portion 3 a of the second member 3. In this manner, even in a configuration in which the first blow-by gas inlet port 31 is provided at a position further up than the first member 2, the first blow-by gas inlet port 31 can be arranged in the vicinity of the first member 2. Therefore, it is possible to easily cause the blow-by gas BG in the vicinity of the first member 2 to flow through the first blow-by gas inlet port 31.

In the embodiment, as described above, the second member 3 is provided with the plurality of cyclone units 34, and the second blow-by gas inlet port 35 through which the blow-by gas BG that has flowed through the first blow-by gas inlet port 31 flows into the plurality of cyclone units 34. In this manner, it is possible to use the path for introducing the blow-by gas BG into the plurality of cyclone units 34 in common by the second blow-by gas inlet port 35. As a result, since the blow-by gas BG can be uniformly distributed to the plurality of cyclone units 34, it is possible to easily improve the separation properties of the oil mist.

In the embodiment, as described above, the second member 3 including the head cover 92 is provided, and the first member 2 including the baffle plate 21 that is arranged to separate the head cover 92 from the cylinder head 91 is provided. In this manner, the oil mist separator 100 integrated with the head cover 92 in which the oil mist separating unit 1 is incorporated between the head cover 92 and the baffle plate 21 can be obtained. As a result, even in a case where the oil mist separator 100 is provided with the first member 2 and the second member 3, it is possible to simplify the structure by preventing the number of components from being increased.

In the embodiment disclosed here, all of the points are merely examples and should be considered not to limit this disclosure. The scope of this disclosure is disclosed not by the description of the embodiment but by the appended claims. Any change (modification example) within the meaning and the scope equivalent to the appended claims is included in the scope of this disclosure.

For example, in the embodiment, a configuration in which the first member 2 includes the baffle plate 21 and the second member 3 includes the head cover 92 has been exemplified, but this disclosure is not limited thereto. In this disclosure, the first member may not include the baffle plate, and the second member may be provided separately from the head cover.

Specifically, as in an oil mist separator 200 according to a first modification example illustrated in FIG. 7, a second member 103 may be provided separately from the head cover 92. In the first modification example, the second member 103 is provided above the head cover 92 and is bonded to the upper surface of the head cover 92. The head cover 92 is provided with a vent hole 104 that supplies the blow-by gas BG to the oil mist separator 200, and an oil discharging unit 105 that returns the separated oil-liquid droplets into the head cover 92 (the cam chamber 94). In the first modification example, a first member 102 includes a part of the head cover 92. The cover member 32 is provided as an individual member that is independent from the head cover 92. The first blow-by gas inlet port 31 is provided at a position further up than the first member 102 and at a lower portion of the side portion 3 a of the second member 103. In this manner, the oil mist separator 200 according to the first modification example is provided outside (upper side of) the head cover 92.

In addition, as in an oil mist separator 300 according to a second modification example illustrated in FIG. 8, a first member 202 and a second member 203 may be provided separately from the head cover 92. In the second modification example, the head cover 92 is provided with a large-size opening portion 204 that is formed to be covered by the oil mist separator 300. The cover member 32 of the second member 203 is provided on the head cover 92, and is bonded to the upper surface of the head cover 92 so as to cover and block the opening portion 204. The first member 202 includes the baffle plate 21 that is arranged inside the opening portion 204. The first blow-by gas inlet port 31 is provided at a position further up than the first member 202 and at a lower portion of the side portion 3 a of the second member 3.

The oil mist separator 200 according to the first modification example and the oil mist separator 300 according to the second modification example can be configured as an individual unit that is independent from the head cover 92, and can be attached to the head cover 92 from the outside.

In the embodiment, a case in which the first blow-by gas inlet port 31 is provided over the whole circumference of the side portion 3 a of the second member 3 has been exemplified, but this disclosure is not limited thereto. In this disclosure, as the third modification example illustrated in FIG. 9, first blow-by gas inlet ports 331 may be configured as a plurality of inlet ports which are separated from each other. In the third modification example, the first blow-by gas inlet ports 331 are respectively provided at lower portions of the side portion 3 a in the X1 side, the X2 side, the Y1 side, and the Y2 side of the second member 3, that is, four first blow-by gas inlet ports 331 are provided in total. Each of the four first blow-by gas inlet ports 331 extends from the center portion of each side of a baffle plate 321 along each side, and is formed to have a predetermined opening width. In the third modification example, unlike the embodiment illustrated in FIG. 5, the baffle plate 321 is formed to have a large size so as to cover an opening on the lower surface side of the inner cover unit 50, and a notch portion 304 corresponding to each of the first blow-by gas inlet ports 331 is formed in each side of the baffle plate 321. As a result, the vicinity of four corners of the first blow-by gas inlet port 31 formed in a peripheral shape illustrated in FIG. 5 is covered, and the first blow-by gas inlet ports 331 opened only at the center portion of each side are formed.

Further, in FIG. 9, multiple first blow-by gas inlet ports 331 may be provided to each side. The number of the first blow-by gas inlet ports 331 is arbitrary. In addition, the first blow-by gas inlet port 331 may not be provided at the center portion of each side. For example, by taking the positional relationship between the first blow-by gas inlet port 331 and the camshaft 93 (refer to FIG. 1) into consideration, a position where the oil-liquid droplets flown up by the camshaft 93 may easily enter is blocked, and the first blow-by gas inlet port 331 may be arranged at a position where the oil-liquid droplets hardly enter.

In the embodiment, a case in which the first blow-by gas inlet port 31 is provided at the lower portion of the side portion 3 a of the second member 3 has been described, but this disclosure is not limited thereto. In this disclosure, the first blow-by gas inlet port may be provided at the upper portion of the outer side surface of the second member. It is preferable that the first blow-by gas inlet port is arranged at a portion further up than the first member.

In the embodiment, a case in which the second blow-by gas inlet port 35 through which the blow-by gas BG flows into the four cyclone units 34 is provided has been exemplified, but this disclosure is not limited thereto. In this disclosure, the second blow-by gas inlet port may not be provided. For example, the two cyclone units 34 and the connection passage 34 a on the X1 side of FIG. 6 are made to face the outside (X1 side), and the two cyclone units 34 and the connection passage 34 a on the X2 side of FIG. 6 are made to face the outside (X2 side). In this manner, the blow-by gas BG may flow through the connection passage 34 a into the cyclone units 34, respectively.

In the embodiment, a case in which the four cyclone units 34 are provided has been exemplified, but this disclosure is not limited thereto. In this disclosure, the number of cyclone units to be provided may be 1 to 3, or equal to or greater than 5.

An oil mist separator according to an aspect of this disclosure is provided at a portion further up than a cylinder head in an internal combustion engine body, and includes an oil mist separating unit that separates oil mist contained in a blow-by gas that is generated from the internal combustion engine body. The oil mist separating unit includes a first member that is arranged in a lower portion and has a partitioning wall shape, and a second member that is arranged above the first member, and includes a first blow-by gas inlet port which is provided at a position further up than the first member and through which the blow-by gas flows into the oil mist separating unit.

In the oil mist separator according to the aspect of this disclosure, the blow-by gas can flow through the first blow-by gas inlet port provided at a position further up than the first member while the cam chamber and the oil mist separating unit are separated by the first member. In this manner, it is possible to suppress entering of the oil scattered from the camshaft or the like into the first blow-by gas inlet port. In addition, even in a case where the oil level of oil is relatively inclined at the time of an uphill climb, it is possible to suppress the covering of the first blow-by gas inlet port by the oil. As a result, suction of the oil into the oil mist separator can be suppressed.

In the oil mist separator according to the aspect of this disclosure, it is preferable that the first blow-by gas inlet ports are provided at multiple locations.

In this configuration, even in a case where any of the first blow-by gas inlet ports provided at multiple locations is covered by oil, the blow-by gas can flow through the first blow-by gas inlet ports provided at other positions. Accordingly, it is possible to further suppress the suction of the oil. In addition, it is possible to easily increase the total opening area of the first blow-by gas inlet ports. As a result, since the flow rate of the blow-by gas in the first blow-by gas inlet port can be reduced, it is possible to suppress the suction of the oil. In the aspect of this disclosure, a plurality of first blow-by gas inlet ports may be separately provided at multiple locations, or a single first blow-by gas inlet port may be provided to be continuous over multiple locations.

In the oil mist separator according to the aspect of this disclosure, it is preferable that the first blow-by gas inlet port is provided in a lower portion of a side portion of the second member.

In this configuration, since the first blow-by gas inlet port can be arranged in the vicinity of the first member even in a configuration in which the first blow-by gas inlet port is provided at a portion further up than the first member, it is possible to easily cause the blow-by gas in the vicinity of the first member to flow through the first blow-by gas inlet port.

In the oil mist separator according to the aspect of this disclosure, it is preferable that the second member includes a plurality of cyclone units, and a second blow-by gas inlet port through which the blow-by gas which has flowed through the first blow-by gas inlet port, flows into the plurality of cyclone units.

In this configuration, a passage that introduces the blow-by gas into the plurality of cyclone units can be used in common by the second blow-by gas inlet port. In this manner, it is possible to uniformly distribute the blow-by gas into the plurality of cyclone units, and thus it is possible to easily improve the separation properties of the oil mist.

In the oil mist separator according to the aspect of this disclosure, it is preferable that the second member includes a cylinder head cover, and the first member includes a baffle plate that is arranged to separate the cylinder head cover from the cylinder head.

In this configuration, it is possible to obtain an oil mist separator integrated with a cylinder head cover in which the oil mist separating unit is incorporated between a cylinder head cover and the baffle plate. As a result, even in a case where the first member and the second member are provided in the oil mist separator, it is possible to simplify the structure by preventing the number of components from being increased.

In this application, the following configurations are also conceivable as the oil mist separator according to the above aspect.

The principles, preferred embodiment and mode of operation of the present invention have been described in the foregoing specification. However, the invention which is intended to be protected is not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. Variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present invention. Accordingly, it is expressly intended that all such variations, changes and equivalents which fall within the spirit and scope of the present invention as defined in the claims, be embraced thereby. 

What is claimed is:
 1. An oil mist separator that is provided at a portion further up than a cylinder head in an internal combustion engine body, the separator comprising: an oil mist separating unit that separates oil mist contained in a blow-by gas that is generated from the internal combustion engine body, wherein the oil mist separating unit includes a first member that is arranged in a lower portion and has a partitioning wall shape, and a second member that is arranged above the first member, and includes a first blow-by gas inlet port which is provided at a position further up than the first member and through which the blow-by gas flows into the oil mist separating unit.
 2. The oil mist separator according to claim 1, wherein the first blow-by gas inlet ports are provided at multiple locations.
 3. The oil mist separator according to claim 1, wherein the first blow-by gas inlet port is provided in a lower portion of a side portion of the second member.
 4. The oil mist separator according to claim 1, wherein the second member includes a plurality of cyclone units, and a second blow-by gas inlet port through which the blow-by gas which has flowed through the first blow-by gas inlet port, flows into the plurality of cyclone units.
 5. The oil mist separator according to claim 1, wherein the second member includes a cylinder head cover, and wherein the first member includes a baffle plate that is arranged to separate the cylinder head cover from the cylinder head.
 6. The oil mist separator according to claim 1, wherein the first blow-by gas inlet ports are provided over the whole circumference of an outer side surface of the second member.
 7. The oil mist separator according to claim 4, wherein the second blow-by gas inlet port is arranged at a portion further up than the first blow-by gas inlet port, and the second member includes a gas passage that extends upward from the first blow-by gas inlet port to be connected to the second blow-by gas inlet port.
 8. The oil mist separator according to claim 4, wherein the second member includes second blow-by gas inlet ports, the number of which is smaller than the number of the multiple locations where the first blow-by gas inlet ports are provided.
 9. The oil mist separator according to claim 4, wherein the second member includes the cyclone unit; a separation structure including the first blow-by gas inlet port and the second blow-by gas inlet port; and a cover member that covers the separation structure and includes a discharge passage of the blow-by gas, and a space portion that is different from the discharge passage is provided between a side surface of the separation structure and the cover member. 